Purpose: The purpose of the Endocrine Core is to advance the study of endocrine abnormalities in drug users with and without HIV infection. This Core will enhance and support research in two primary areas of complications in drug users living with HIV and it's therapies: 1) endocrine abnormalities and sexual dysfunction and 2) glucose metabolism abnormalities such as insulin resistance which may result in long term complications such as cardiovascular disease. Specifically, this Core will: 1) Work with investigators to develop hypotheses, giving advice on the most suitable parameters to be used in studies of endocrine factors; 2) Provide questionnaires and/or case report forms, as well as training on how to document the clinical signs and symptoms of sexual function, gonadal and adrenal disease, and other metabolic abnormalities; 3) Provide endocrine laboratory support that is as responsive and as comprehensive as possible to meet the future needs of investigators. This includes running endocrine assays for gonadal, adrenal, and metabolic testing, including total and free testosterone, FSH, LH, and prolactin and cortisol, ACTH, DHEA, aldosterone, glucose and insulin; and 4) Give advice on the analysis and interpretation of data from the above procedures.